Anti-stall device



y 23, 1951 R. J. BRUNNER 2,985,196

ANTI-STALL DEVICE Filed NOV. '7, 1958 )2 INVENTOR.

fizaarddflumrzz ANTI-STALL DEVICE Richard J. Brnnner, Rochester, N.Y., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Nov. 7, 1958, Ser. No. 772,474

4 Claims. (Cl. 137-790) The present invention relates to an improved carburetor anti-stall device of the type adapted to be controlled by manifold vacuum. In this type of anti-stall device a diaphragm actuated stop member is adapted to engage with a throttle lever such that upon a sudden drop in manifold vacuum a spring member will cause the stop to move the throttle to a more open position or to prevent the throttle from closing too rapidly and thereby prevent engine stalling.

A difiiculty arises with such a vacuum actuated antistall device when the engine is lightly loaded, the throttle only slightly opened, and the accelerator pedal released tending to close the throttle. Under these conditions manifold vacuum is high and the stop member out of engagement with the throttle lever and, consequently, such member is inoperative to delay closing of the throttle. Also, under this condition, the fuel-air ratio is rather rich and not rapidly digestible by the engine without a slight time delay in the throttle closing. The previous vacuum actuated anti-stall devices have been unable to provide the requisite throttle closing time delay under these specific operating conditions as a consequence of which engine stalling is experienced.

The present device represents an improvement in such an anti-stall device in which a secondary dashpot action is achieved which prevents stalling under the light throttle conditions just described. In the present device the vacuum actuated stop member is provided with a plunger therein which projects axially beyond the normal stop and is held in such extended position by a light spring member. Thus when the stop is rendered inoperative due to high vacuum, the plunger remains in an extended position and will engage the throttle lever when it moves in a throttle closing direction to delay slightly the closing of the throttle and to prevent engine stalling under the light throttle-high vacuum condition described.

While illustrated in a carburetor environment, it is apparent that the present invention has utility with other devices where similar control is desired.

The details as well as other objects and advantages of the present invention will be apparent from a perusal of the detailed description which follows.

In the drawings:

Figure 1 is a sectional view of the subject anti-stall device; and

Figure 2 is an enlargement of a portion of Figure l.

The anti-stall device is indicated generally at and includes a pair of casing members 12 and 14 peripherally clamping a flexible diaphragm member 16 therebetween. Diaphragm 16 has a pair of reinforcing washers 18 fixed centrally thereof and provide support for a sleeve member 20. Casing 14 has a central opening within which a bushing 22 is mounted. Sleeve 20 is slidably supported within bushing 22.

Casing 12 has a central opening within which a fitting 24 is fastened. 'Fitting 24 is adapted to communicate through a conduit 26 with a source of manifold vacuum. For reasons which will subsequently be more apparent,

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a seat 28 is formed in fitting 24 and is adapted to receive a ball check valve 30. When the engine is operating under normal load conditions the manifold vacuum acting through conduit 26 will normally. cause ball check valve 30 to rest upon its seat 28. Under these conditions, chamber 32 defined by casing 12 and diaphragm 16 will be evacuated through a restricted bypass passage 34 formed in fitting 24, gradually overcoming the force of a spring 36 disposed in chamber 32 and causing diaphragm 16 to move the sleeve 20 to the left. 0n the other hand, when manifold vacuum falls ofl, spring 36 will move diaphragm 16 to the right causing valve 30 to become unseated and permitting air to enter chamber 32 through large passage 38. Thus the leftward movement of diaphragm 16 is adapted to take place at a considerably slower rate than the rightward movement for a reason which will be subsequently considered.

A screw stop member indicated generally at 40 is threadably received within sleeve 20. Screw 40 includes a head 42 adapted to be engaged by an accelerator pedal or throttle lever 44 suitably articulated to a carburetor 46. Carburetor 46 includes a throttle valve 48 and a lever 50 fixed thereto. As throttle valve 48 is moved in a closing direction, represented by a leftward movement of the lever 44, the latter lever will engage stop 40 before the valve reaches a closed position. Thus, as already described, under normal engine load conditions, the manifold vacuum in chamber 32 is suificiently high to overcome the force of spring 36 to normally move stop screw 40 to an inoperative position relative to the lever 44. Further, should the manifold vacuum fall olf, indicative of a high engine load, stop 40 will be moved to the right by spring '36 to engage with lever 44 to either open throttle valve 48 or to prevent the same from being closed too rapidly and to thereby eliminate engine stalling.

As already suggested, there is a condition when manifold vacuum is high, indicative of light engine loads, when the throttle valve may be slightly opened leaving the diaphragm and hence stop screw 40 in an inoperative or leftmost position, as seen in Figure 1. Under this condition a sudden release of the accelerator pedal will tend to cause the throttle valve to close quickly making stalling likely.

To prevent the sudden throttle closing under these conditions, a longitudinal opening 52 is provided within screw 40 and a plunger member 54 slidably disposed therein. A light spring member 56 is disposed within screw opening 52 and biases plunger 54 in an outwardly direction toward the lever 44. Plunger 54 is peripherally relieved at 58 to cooperate with a stop pin 60 provided in screw 40. Pin 60 limits the outward travel of plunger 54 thereby preventing the same from becoming disassembled from the screw. Thus it will be seen that when manifold vacuum is of such a value as to retain stop screw 40 in its inoperative position relative to lever 44, plunger 54 will be in its extended position. Under these conditions, should throttle valve 48 endeavor to be closed quickly, lever 44 will engage plunger 54 and the closing movement of the throttle will be resisted by the force of spring 56. As noted, spring 56 is of a very light construction and will eventually be overcome by the throttle valve closing spring, not shown, whereby lever 44 will abut head 42 of screw 40. However, the spring action will none the less delay the closing of the throttle valve until the engine has had time to consume any excess fuel after which the engine may idle properly and without stalling.

It is apparent that the present device provides a twostage type anti-stall mechanism adapted to prevent too sudden throttle closing either under high or light engine load conditions and which ability represents an improvement over previous type anti-stall mechanisms..

I claim:

1. An anti-stall mechanism comprising a pair of casing members, a diaphragm peripherally clamped between said casing members, a sleeve member centrally supported upon said diaphragm and extending through an opening in one of said casing members, a stop member adjustably supported Within said sleeve member, a chamber defined by said diaphragm and the other of said casing members, spring means disposed within said chamber and normally biasing said diaphragm to a position extending said sleeve beyond one of said casing members, conduit means communicating with said other casing member and adapted for supplying vacuum to said chamber to act on said diaphragm and overcome said spring means to urge the diaphragm to a position adapted to retract said sleeve within the associated casing member, said stop member including a longitudinal opening therein, a plunger element disposed within said longitudinal opening, a spring member disposed within said longitudinal opening and adapted to bias said plunger axially outwardly with respect to said stop member, and means for limiting the outward travel of said plunger.

2. An anti-stall mechanism comprising a pair of casing members, a diaphragm peripherally clamped between said casing members, a sleeve member centrally supported upon said diaphragm and extending through an opening in one of said casing members, a stop member adjustably supported Within said sleeve member, a chamber defined by said diaphragm and the other of said casing members, spring means disposed within said chamber and normally biasing said diaphragm to a position extending said sleeve beyond one of said casing mem bers, conduit means communicating with said other casing for supplying vacuum to said chamber to act on said diaphragm and overcome said spring means to urge the diaphragm to a position adapted to retract said sleeve within the associated casing member, said stop member including a first stop surface rigidly fixed thereto, a

plunger axially movable relative to said member, said plunger including a second stop surface, and means biasing said second stop surface axially beyond said first surface.

3. An anti-stall mechanism comprising a pair of easing members, a diaphragm peripherally clamped between said casing members, a sleeve member centrally supported upon said diaphragm and extending through an opening in one of said casing members, a stop member adjustably supported within said sleeve member, a chamber defined by said diaphragm and the other of said casing members, spring means disposed within said chamber and normally biasing said diaphragm to a position extending said sleeve beyond one of said casing members, conduit means communicating with said other casing for supplying vacuum to said chamber to act on said diaphragm and overcome said spring means to urge the diaphragm to a position I adapted to retract said sleeve Within the associated casing member, said stop member including a first stop surface rigidly fixed thereto, a plunger axially movable relative to said member, said plunger including a second stop surface, and means biasing said second stop surface axially beyond said first surface, and means limiting the axial movement of said second stop surface beyond said first surface.

4. An anti-stall mechanism as set forth in claim 1 in which said plunger travel limiting means comprises a longitudinally extending relieved portion formed in the periphery of said plunger, and a pin element mounted in said stop member and extending within said longitudinal opening, said pin element adapted to coact with said plunger relieved portion to limit outward travel of the plunger.

References Cited in the file of this patent UNITED STATES PATENTS 2,762,615 Cedarholm Sept. 11, 1956 

